president, i am bringing to you and to the people of the united states the gratitude of the afghan people. >> reporter: leaders of nato joined president obama for dinner at soldier field, the iconic stadium for his beloved chicago bears. he is asking something more from them. money. the cost of supporting the afghan military after nato leaves is estimated to be $4 billion a year for ten years. after the last american combat troops pull out. ann compton, abc news, chicago. >> you know, we saw a little bit of the protests in her piece. what we're hearing is they were expecting 10,000 people to show up and only 3,000 people showed up, which i guess for the police that had to control this massive crowd was good. but at the same time, these people are very upset about what they want to get out there and some of the protesters actually interfered with commuters and traffic. so quite a big deal for chicago. first time it's been held there in a long time. >> a mess but not as bad as it could be. the big thing to come out of the summit is leaders greeg do something to stabilize the oil market beca